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Publication Abstract from PubMed

The three dimensional structure of calcium-bound domain VI of porcine calpain has been determined to 1.9 A resolution. The crystal structure reveals five EF-hands, one more than previously suggested. There are two EF-hand pairs, one pair (EF1-EF2) displays an 'open' conformation and the other (EF3-EF4) a 'closed' conformation. Unusually, a calcium atom is found at the C-terminal end of the calcium binding loop of EF4. With two additional residues in the calcium binding loop, the fifth EF-hand (EF5) is in a 'closed' conformation. EF5 pairs up with the corresponding fifth EF-hand of a non-crystallographically related molecule. Considering the EF5's role in a homodimer formation of domain VI, we suggest a model for the assembly of heterodimeric calpain. The crystal structure of a Ca2+ bound domain VI-inhibitor (PD150606) complex has been refined to 2.1 A resolution. A possible mode for calpain inhibition is discussed.

Crystal structure of calcium bound domain VI of calpain at 1.9 A resolution and its role in enzyme assembly, regulation, and inhibitor binding.,Lin GD, Chattopadhyay D, Maki M, Wang KK, Carson M, Jin L, Yuen PW, Takano E, Hatanaka M, DeLucas LJ, Narayana SV Nat Struct Biol. 1997 Jul;4(7):539-47. PMID:9228946^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.